Alternator/voltage regulator

[RonLange]

my 93 regal's dash voltmeter is wavering like crazy, especially when the weather turns cold. it drops to about 9-10 volts then up to 17 or maybe back to 13, just all over the place. does this need a new alternator? i've heard their regulators are part of the alternator.

 

[Syndicated]

my grandfathers 91 regal does the same thing, as does the oil pressure guage. 99% of the time it's nothing to worry about at all, and has nothing to do with the alternator. The guage cluster in most early GMs are very erratic.
If you notice your headlights and/or dashlights are dimmer, or power windows go up slower, especially at idle - then you may have a problem. If you're mechanically inclined, you can check the alternator output yourself, however, if not, go to a shop and they'll be able to check your charging system and let you know if your alternator is bad.

 

[RonLange]

yes, in fact i am a mechanic. but this is the first GM car i've owned, so i'm not quite up on their quirks and details. but i am sure its not the gauge cluster because everything electrical goes dim/bright in relation to the volt gauge. so if i check alt. output on my multimeter, and it also goes up and down like the gauge does that mean it's internal regulator is shot? that's kinda what i'm thinking, i just don't wanna go buy parts i don't need of course.

 

[Syndicated]

if all your lights dim in relation to the guage's movement, I would have to say the regulator is *starting* to go.
The reason why I sugested the guages before is because on my grandfathers car, his guage was doing that, and coincidently, the alternator died anywayz, so after changing it, the guage was still acting erratic. Yet, before and after changing the part, the lights never dimmed!
As for GM's in general, their alternators and water pumps I would say are their weakest points - under the hood anywayz.

I know what you're saying about not knowing the quirks about GMs, I'm actually a Ford apprentice technician (sshh!!) I know a helluva lot more about any Ford than a GM product. Thats the thing about the trade though, there's always more to learn!